Computers generally utilize disk drives for data storage and retrieval, such as magnetic recording hard disk drives that utilize a head assembly for reading and/or writing data on a rotatable magnetic disk. In such systems, the head assembly is typically attached to an actuator arm by a head suspension assembly (HSA) comprising a head suspension and an aerodynamically designed slider onto which a read/write head is provided. When the head is positioned over a spinning disk during usage, the head position is at least partially controlled by balancing a lift force that is caused by an air bearing generated by the spinning disk and acting upon the slider, and an opposite bias force of the head suspension. In operation, the slider and head are designed to “fly” over the spinning disk at high speeds and at precisely determined distances from the disk surface.
Head stack assemblies (HSAs) typically include a plurality of head gimbal assemblies (HGAs), a rotary actuator, and a flex cable. The mounting plate of each suspension assembly is attached to an arm of the rotary actuator (e.g. by swaging), and each of the laminated flexures is electrically connected to the HSA's flex cable (e.g. by solder reflow bonding or ultrasonic bonding). The angular position of the HSA, and therefore the position of the read heads relative to data tracks on the disks, is actively controlled by the rotary actuator which is typically driven by a voice coil motor that allows the read/write head to seek and follow desired data tracks on a spinning disk.
The rotary actuator of the HSA is pivotally attached to a base of the disk drive, such as by an actuator pivot bearing that allows the HSA to pivot. The positioning of other disk drive components limits the pivoting to a limited angular range. The actuator pivot bearing is typically mounted to the base of the disk drive by a first screw that extends upwardly through the bottom of the base and a second screw that extends downwardly through the top cover of the disk drive. Such a configuration can be useful for typical air drives, but the two screw design can provide for areas through with the helium can leak. In addition, when certain configurations of this type are used for helium drives, the torque and stiffness of the pivots can be sensitive to cover screw tension. Large changes in pivot torque and stiffness can affect actuator performance and impact actuator controls. There is a desire in the art for a helium disk drive in which the torque and stiffness sensitivities are reduced.